Nowadays common structures made of wood or steel have a construction of solid combination by means of nails, bolts or welding, so they are not easily taken apart for reconstructing at somewhere else once they have been constructed. Trusses made of wood may become rotten owing to wet weather or insects after several years of use, so keeping them always in good shape would be difficult and troublesome. In addition, necessary processes in treating them for protection from moisture and corrosion are inconvenient. Especially, they are not suitable for export to foreign countries because of heavy weight and large volume.
Structures made of steel are commonly welded together, but they are vulnerable to moisture as well, and painting processes for resisting rust are complicated and not durable as long as paints peel off over time, especially in an island country. Moreover, they do not have an advantageous structure for mass production, so they cannot be exported to compete in the international market. In view of the above-mentioned drawbacks, the inventor has worked out this new structure.